Deteriorating health. Healthy again.

Hello doctor! i am 24years old. since 3years I'm constantly getting weak. my physical health is deteriorating. from 53kg i have come down to 46kg. my height is 5feet 3inches. i have become very skinny. the problem basically is that people have started telling me that i look as if I'm suffering from some disease. not only this my diet too is decreasing day by day. i would like to inform you also that i have been suffering from severe headaches from last 2-3 months which lasts for 2-3mins. these headaches have become quite frequent now and they tend to surface in the evening or night time only. please help me know if my health is in anyway related to this headache or not and also what can i do to become healthy again. thank you.